Amphibious vehicle

ABSTRACT

Amphibious vehicle comprises longitudinally mounted prime mover, transmission, and offset final drive; with drive outputs; and a power take off. Outputs drive front and rear differentials, via optional decouplers. Power take off powers drive tube, independently from co-axial rear propshaft. Tube powers sprockets via belt or chain; gears could be used here. Optional marine decoupler drives shaft, and thus water jet pump. A power train with front wheel drive only; a dead rear axle is provided. A power train with rear wheel drive only; a dead front axle is provided. Prime mover may be offset parallel to centre line; and may be an engine or an electric motor, possibly powered by a fuel cell. The power take off may be in the form of a drive spline.

The present invention relates to an amphibious vehicle capable of travelon land and water, and more particularly to an amphibious vehicle inwhich a conventional automotive transaxle drive arrangement is adaptedto drive at least one pair of road wheels and a marine propulsion means.

In some known automotive power train arrangements the prime mover has apower output shaft, typically an engine crankshaft, which is alignedsubstantially perpendicular to the longitudinal axis of the vehicle.This is known as a transverse engine layout. Normally, the engine willdrive a transmission arranged in-line with the axis of the crankshaftand which has all integral final drive and differential offset to therear of the engine, the differential being connected by drive shafts tothe drive wheels of the vehicle. This arrangement is commonly known as atransaxle drive and is usually employed with the engine located towardsthe front of the vehicle in order to drive the front wheels of avehicle. It is also known for such transverse power train arrangementsto be adapted to provide four wheel drive by having a power take offfrom the transmission which drives the rear wheels of the vehiclethrough a rear differential.

FIG. 1 is a schematic plan view of a vehicle, indicated generally at 10,having a such a known four wheel drive transverse engine and transaxlearrangement. As can be seen, an engine 12 is mounted. transversely, thatis with the crankshaft of the engine perpendicular to the longitudinalaxis of the vehicle, indicated at 15, forward of a pair of front wheels14, 16 of the vehicle 10. A transmission 18 is mounted in-line with andis driven by the engine 12. Transmission 18 drives a final drive, 20which is offset to the rear of the vehicle. The final drive, 20incorporates a differential and the front wheels 14, 16 are driven fromthe differential by means of respective drive shafts 22, 24 which maycomprise CV joints (not shown) as is known in the art.

In order to provide for four wheel drive, the final drive has a drivespline 26 which drives a power take off unit 28. A propeller shaft 30 isconnected to the power take off unit 28 and transmits drive to a reardifferential 32, from which the rear wheels 34, 36 are driven throughrespective drive shafts 38, 40.

Four wheel drive, transverse engine, and transaxle drive units of thetype shown in FIG. 1 are currently used by several large carmanufacturers in the production of private passenger vehicles and aretherefore produced in relatively high volumes, which makes thearrangement most procurable for use in an amphibious vehicle. Inchoosing a power train for a specialised low volume production vehicle,such as an amphibious vehicle, availability is an important factor.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an amphibiousvehicle in which a conventional four wheel drive transverse engine andtransaxle unit is adapted to drive at least one pair of road wheels anda marine drive means.

In accordance with the invention, there is provided an amphibiousvehicle having a power train comprising a prime mover, transmission,final drive, and a marine propulsion means, the final drive having apower take off, characterised in that: the prime, mover is positioned.with its output drive shaft arranged generally longitudinally of thevehicle and the final drive is arranged to drive at least one pair ofroad wheels of the vehicle through a differential, and in that the powertake off is adapted to drive the marine propulsion means via a drivetable.

Preferably, the power take off comprises a drive spline which drivinglyengages one end of the drive tube.

Preferably, the final drive is arranged to drive a pair of front wheelsof the vehicle through a front differential. Alternatively, the finaldrive is arranged to drive a pair of rear wheels of the vehicle througha rear differential.

Conveniently, the final drive is arranged to drive two pairs of roadwheels of the vehicle, each pair of road wheels being driven through arespective differential.

Advantageously, the drive tube is co-axial with a drive shaft whichtransmits drive from the final drive to a differential.

Preferably, one or more decoupler(s) is/are provided to allow decouplingof drive to the road wheels, where said decoupler(s) is/are locateddownstream of the transmission.

Advantageously, the prime mover is positioned such that its output driveshaft is generally in alignment with the longitudinal axis of thevehicle.

The prime mover may be an engine or an electric motor, the motor may bepowered by a fuel cell.

Preferably, the final drive comprises at least one drive output, theaxis of the at least one drive output being substantially parallel with,but offset laterally from, the axis of the prime mover output driveshaft.

It is an advantage of the present invention that a conventionaltransverse engine and transaxle drive unit can be utilised and adapted.It is a further advantage that the conventional transverse engine andtransaxle drive unit can be positioned between, the front and rearwheels of the amphibious vehicle, and close to the rear of the vehicle,giving a rearward weight bias to the vehicle which is required for anoptimum marine performance particularly when planing.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, withreference to the Figures of the accompanying drawings in which:

FIG. 1 is a schematic view of a prior art vehicle;

FIG. 2 is a schematic plan view of an amphibious vehicle having a powertrain in accordance with a first embodiment of the invention;

FIG. 3 is a schematic plan view of an, amphibious vehicle having a powertrain in accordance with a second embodiment of the invention; and

FIG. 4 is a schematic plan view of an amphibious vehicle having a powertrain in accordance with a third embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 2 to 4 show various embodiments of an amphibious vehicle inaccordance with the invention, in which the conventional engine 12,transmission 18 and final drive 20 arrangement as described in relationto FIG. 1 has been utilised and adapted. Common reference numerals havebeen used throughout to designate parts in common with parts shown inFIG. 1.

Referring firstly to FIG. 2, there is shown an amphibious vehicle 41having a power train 42 in which an engine 12, with an in-linetransmission 18 and offset final drive 20 are positioned with thecrankshaft of the engine in alignment with the longitudinal axis 44 ofthe vehicle. The final drive 20 incorporates a differential having driveoutputs 21, 23. A rear differential 48 is connected to one of the driveoutputs 21 by means of a propeller shaft 52 and drives a pair of rearwheels 34, 36 of vehicle through drive shafts 3 8, 40 and relay shaft39. A forward differential 46 is connected to the other of the driveoutputs 23 by a further propeller shaft 50 and drives front wheelpropeller shaft 50 and drives front wheels 14, 16, by means of driveshafts 22, 24 and a relay 25. The road wheel drive shafts may compriseCV joints (not shown) as required.

In order to enable selective engagement of drive to the front and rearwheels independently, a front decoupler 54 is positioned in the driveline between the propeller shaft 50 and the front differential 46, and arear decoupler 56 is positioned. in the drive line between the propellershaft 52 and the rear differential 48. The front and rear differentials46,48 can therefore, be selectively coupled and decoupled from the finaldrive differential 20.

Although not shown, an alternative arrangement for selectively couplingdrive to the front and rear wheels independently comprises providing adecoupler in the drive line between each of the front and reardifferential 46, 48 and at least one of the road wheels driven by therespective differential. In this alternative arrangement, the decouplers54, 56 as shown in FIG. 2 are not required, and the front and reardifferentials 46, 48 are driven directly from the final drive 20 bytheir respective propeller shafts 50, 52. Where a decoupler isincorporated into a drive line between a differential and a road wheel,the decoupler may be fitted in series or in combination with a CV jointused in the drive line. For example a combined CV joint and decouplerarrangement such as that disclosed in the applicant's co-pendingInternational patent application PCT/GB01/03493 could be used.

Drive for a marine propulsion means, which in this case is a water jet70, is also taken from the final drive 20 by means of a drive tube 58positioned around, and co-axial with the propeller shaft 52, which runsat the side of and parallel with the engine 12. One end of the drivetube 58 is splined, and mates with a drive spline 26 provided on aspline carrier. The spline carrier is arranged concentrically about thedrive output 21 of the final drive 20 and the arrangement is such thatthe drive tube 58 is driven by the drive spline 26 independently of thepropeller shaft 52. The other end of the drive tube 58 drives a drivingsprocket 60. A sprocket 62 is driven by a belt or chain 64 from thedriving sprocket 60, and is connected by a decoupler 66 to a drive shaft68 of a water jet unit 70. The decoupler 66 enables the driven sprocketto be selectively coupled and decoupled to or from the drive shaft 68,in order to allow drive to the water jet to be disconnected when thevehicle is being operated on land and marine drive is not required.

A bearing (not shown) may be required to locate the rear end of tube 58,and sprocket 60. As an alternative to the sprockets and belt or chainshown, a series of typically three gears could be used to transfer drivefrom tube 58 to shaft 68. Whilst a water jet is the preferred form ofmarine propulsion means, this is not essential and the water jet may bereplaced with any suitable marine propulsion means, for example a inmarine screw propeller.

In this and the other embodiments described below, the final drive has apower takeoff in the form of a drive spline formed on a spline carrierand the drive tube is provided at one end with a corresponding, splinefor engagement with the drive spline. However, those skilled in the artwill understand that means other than a drive spline can be used totransfer drive from the power take off carrier to the drive tube. Forexample the carrier and the drive tube could be provided withinter-engagning lugs or gear teeth. Alternatively, the drive tube couldbe welded, bolted or otherwise secured to the carrier.

Referring now to FIG. 3, a second embodiment of an amphibious vehicle141 in accordance with the invention comprises a power train 142. Thepower train arrangement 142 shown in FIG. 3 is generally similar to thepower train 42 as described above with reference to FIG. 2, the maindifference being that only the front wheels 14, 16 of the vehicle aredriven from the final drive 20. Thus, propeller shaft 52, decoupler 56and rear differential 48 of the FIG. 2 arrangement are omitted, as theyare not required in this embodiment. In place of the live, or drivenaxle shown in FIG. 2, a dead, or non-driven axle 72 is fitted to therear of the vehicle. Alternatively, the rear wheels can be independentlymounted to the vehicle body or chassis.

CV joints 74, 76 are incorporated in the drive line between the frontdifferential 46 and each of the front wheels. Decouplers may be fittedin series or in combination with these CV joints, in order to decouplethe front wheels from the transmission during marine use.

Referring now to FIG. 4, a third embodiment of an amphibious vehicle′241in accordance with the invention comprises a power train 242. The powertrain arrangement 242 shown in FIG. 4 is generally similar to the powertrain 42 described above in relation to FIG. 2, the main differencebeing that only the rear wheels are driven from the final drive 20.Thus, in the power train 242, propeller shaft 50, decoupler 54 and frontdifferential 46 are omitted, as they are not required. In place of thelive, or driven axle shown in FIG. 2, a dead, or nondriven axle 82 isfitted to the front of the vehicle. Alternatively, the front wheels canbe independently mounted to the vehicle body or chassis,

CV Joints 84, 86 are located in the drive line between the reardifferential and each of the rear wheels. Decouplers may be fitted inseries or in combination with these CV joints, in order to decouple therear wheels from the transmission during marine use.

In the second and third embodiments described above with respect toFIGS. 3 and 4, if the final drive 20 incorporates a differential, thenthe differential is locked up so that only the fitted propeller shaft 50or 52 is driven. It should be noted that either of these arrangementscould be suited to a three-wheeled vehicle. Equally, the firstembodiment could be adapted to use in a six-wheeled vehicle by use of atandem rear axle.

In all the embodiments of the invention described above, the prime moveris provided the form of an engine. The engine can be of any suitabletype and may comprise a piston engine, a rotary engine or turbine andcan be adapted to run on any suitable fuel such as petrol, diesel, gas,or liquid petroleum gas (LPG). However, it should be understood that theinvention is not limited to power trains in which the prime mover is anengine but is intended to cover power trains having a prime mover of anysuitable type. For example the prime mover could be an electric motor orit could be in the form of a hybrid combination of an engine with anelectric motor. Where the prime mover comprises an electric motor, theelectric motor could, for example, be powered by a fuel cell.

Whereas the invention has been described in relation to what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not limited to thedisclosed arrangements but rather is intended to cover variousmodifications and equivalent constructions included within the spiritand scope of the invention as defined in the claims. For example, itwill be appreciated that further combinations of driven axles anddecoupler locations may be selected from the options disclosed above.Also, whilst it is preferred that decouplers are provided in the driveline between the transmission and the driven road wheels, this is notessential and the decouplers, can be omitted. Similarly, whilst it ispreferred that a decoupler be provided to enable drive the marinepropulsion means to be disconnected when the vehicle is being used in aland mode, this is not essential and the marine propulsion meansdecoupler can be omitted if desired. Furthermore, whilst in theembodiments described the output shaft of the prime mover is shown inalignment with the longitudinal axis of the vehicle, this need not bethe case and the output shaft could be arranged so as to lie generallyparallel to, but offset from, the longitudinal axis of the vehicle ifrequired.

1. An amphibious vehicle having a power train comprising; a prime mover;a transmission; a final drive having a power take off; and a marinepropulsion means; wherein: the prime mover is positioned with its outputdrive shaft arranged generally longitudinally of the vehicle; the finaldrive is arranged to drive at least one pair of road wheels of thevehicle through a drive shaft and differential; the power take off isadapted to drive the marine propulsion means via a drive tube thatextends alongside the prime mover; and and the drive tube issubstantially co-axial with said drive shaft which transmits drive fromthe final drive to said differential.
 2. An amphibious vehicle asclaimed in claim 1, in which the power take off comprises a drive splinewhich drivingly engages one end of the drive tube.
 3. A power train asclaimed in claim 1 in which the final drive is arranged to drive a pairof front wheels of the vehicle through and a front differential.
 4. Apower train as claimed in claim 1, in which the final drive is arrangedto drive a pair of rear wheels of the vehicle through a reardifferential.
 5. An amphibious vehicle as claimed in claim 1, in whichthe final drive is arranged to drive two pairs of road wheels of thevehicle, each pair of road wheels being driven through a respectivedifferential.
 6. An amphibious vehicle as claimed claim 1, in which atleast one decoupler is provided to allow decoupling of drive to the roadwheels, where said decoupler is located downstream of the transmission.7. An amphibious vehicle as claimed in claim 1, in which the prime moveris positioned such that its output drive shaft is generally in alignmentwith the longitudinal axis of the vehicle.
 8. An amphibious vehicle asclaimed in claim 1, in which the prime mover is an engine.
 9. Anamphibious vehicle as claimed in claim 1, in which the prime mover is anelectric motor.
 10. An amphibious vehicle as claimed in claim 9, inwhich the electric motor is at least partially powered by a fuel cell.11. An amphibious vehicle as claimed in claim 1, in which the finaldrive comprises at least one drive output, the axis of the at least onedrive output being substantially parallel with, but offset laterallyfrom, the axis of the prime mover output drive shaft.
 12. An amphibiousvehicle as claimed in claim 1, in which said drive shaft extends throughsaid drive tube.
 13. An amphibious vehicle having a power traincomprising: a prime mover; a transmission; a final drive having a powertake off; a marine propulsion means, wherein the prime mover ispositioned with its output drive shaft arranged generally longitudinallyof the vehicle; the final drive is arranged to drive at least one pairof road wheels of the vehicle through a drive shaft offset laterallyfrom the axis of the prime mover output drive shaft and through adifferential; the power take off is adapted to drive the marinepropulsion means via a drive tube that extends alongside the primemover; and said drive shaft extends from said final drive in asubstantially opposite direction to said drive tube.
 14. An amphibiousvehicle as claimed in claim 13, wherein the power take off comprises adrive spline which drivingly engages one end of the drive tube.
 15. Apower train as claimed in claim 13, wherein the final drive is arrangedto drive a pair of front wheels of the vehicle through said drive shaftand a front differential.
 16. An amphibious vehicle as claimed in claim13, wherein at least one decoupler is provided to allow decoupling ofdrive to the road wheels, where said decoupler is located downstream ofthe transmission.
 17. An amphibious vehicle as claimed in claim 13,wherein the prime mover is positioned such that its output drive shaftis generally in alignment with the longitudinal axis of the vehicle. 18.An amphibious vehicle as claimed in claim 13, wherein the final drivecomprises at least one drive output, the axis of the at least one driveoutput being substantially parallel with, but offset laterally from, theaxis of the prime mover output drive shaft.